add non-regression test for issue 122674

Author: lqd

tests/ui/fmt/issue-122674-nested-await.rs

@@ -0,0 +1,22 @@
+// Non-regression test for issue #122674: a change in the format args visitor missed nested awaits.
+
+//@ edition: 2021
+//@ check-pass
+
+pub fn f1() -> impl std::future::Future<Output = Result<(), String>> + Send {
+    async {
+        should_work().await?;
+        Ok(())
+    }
+}
+
+async fn should_work() -> Result<String, String> {
+    let x = 1;
+    Err(format!("test: {}: {}", x, inner().await?))
+}
+
+async fn inner() -> Result<String, String> {
+    Ok("test".to_string())
+}
+
+fn main() {}